Conventionally, in production of packaging containers that contain liquid food such as milk or soft drink, a web-like packaging material formed from a flexible laminate material is formed into a tubular shape by means of a preforming apparatus, and the tubular packaging material is sealed and cut at predetermined intervals while being filled with liquid food, thereby yielding brick-like packaging containers.
FIG. 1 is a schematic view of a conventional filling apparatus.
In FIG. 1, reference numeral 11 denotes a web-like packaging material formed from a flexible laminate material. The packaging material 11 is produced by means of an unillustrated packaging-material-producing machine and is set in the form of a reel 12 on a delivery unit 13. The packaging material 11 is delivered by means of the delivery unit 13 and is caused to travel through the filling apparatus by means of a feed apparatus.
While the packaging material 11 is traveling, an unillustrated hole is punched in the packaging material 11, and an unillustrated inner tape and an unillustrated pull tab are affixed to the packaging material 11 in such a manner as to cover the punched hole. Subsequently, the packaging material 11 is caused to travel vertically. While being guided by means of a plurality of forming rings 15 disposed along the traveling direction, the vertically traveling packaging material 11 is formed into a tubular shape such that opposite side edges thereof overlap each other by a predetermined overlap quantity. A portion where the opposite side edges overlap each other; i.e., an overlap portion, is sealed in the longitudinal direction by means of an unillustrated longitudinal sealing device.
While the packaging material 11 is guided by means of a tube guide roller 17, liquid food is supplied from above to the tubular packaging material 11 via a filling pipe 16. Next, while being gripped from opposite sides by means of sealing jaw devices, the packaging material 11 is laterally sealed at predetermined longitudinal intervals and is formed into a pillow-like prototype container 18 through deformation effected by unillustrated forming flaps. The sealing jaw devices constitute a lateral sealing device.
Subsequently, each prototype container 18 undergoes cutting at a laterally sealed portion; i.e., a lateral seal portion, and folding along previously formed folding lines so as to be formed into a predetermined shape, thereby assuming the form of a brick-like packaging container which contains a predetermined amount of liquid food.
The feed apparatus generally includes a pair of nip rollers R1 (FIG. 1 shows only one of the paired nip rollers) disposed adjacent to the delivery unit 13 and adapted to feed the packaging material 11 while nipping the packaging material 11 from front and rear sides; unillustrated crease rollers for forming creases on the packaging material 11 while the same is being rotated; a pair of nip rollers R2 (FIG. 1 shows only one of the paired nip rollers) disposed at the highest position of the filling apparatus and adapted to feed the packaging material 11 while nipping the packaging material 11 from front and rear sides; and unillustrated engagement portions formed integrally with the corresponding forming flaps and adapted to engage lugs formed on the prototype container 18 in the vicinity of the lateral seal portions so as to move the prototype container 18 and the packaging material 11 forward as the forming flaps move.
The tube guide roller 17 includes at least two support rollers. Each of the support rollers has a predetermined curved surface for guiding the packaging material 11.
Meanwhile, in the filling apparatus, the traveling web-like packaging material 11 can be positioned in a relatively easy manner by means of unillustrated guide members which are formed in correspondence with opposite side edges of the packaging material 11. However, positioning the traveling tubular packaging material 11 is difficult, since the packaging material 11 is curved.
Upon reception of force from the feed apparatus, the tubular packaging material 11 may move in a circumferential direction, with a resultant deviation of the overlap portion from a predetermined position. In order to cope with the problem, an unillustrated movable guide roller, an unillustrated movable forming ring, and the like are disposed along a travel path of the packaging material 11 so as to correct the position of the overlap portion through operation of the movable guide roller, the movable forming ring, and the like.
In this case, the movable guide roller is disposed upstream of the forming rings 15 in the traveling direction of the packaging material 11. Furthermore, the movable forming ring is disposed in the vicinity of a forming ring 15 disposed on the upstream side among the plurality of forming rings 15. Since the packaging material 11 which has undergone correction for the position of the overlap portion is fed to the downstream forming ring 15, the tubular packaging material 11 can travel stably through employment of the following mechanism: among forming rollers of the forming ring 15, a predetermined forming roller has a flange formed thereon, and the flange lightly presses a side edge portion of the packaging material 11.
However, in the conventional filling apparatus, when the packaging material 11 of a certain size is to be corrected for the position of the overlap portion through operation of the movable guide roller, the movable forming ring, and the like, a side edge portion of the packaging material 11 impinges on the flange, and thus the flange interferes with correction on the position of the overlap portion. As a result, an attempt to correct the position of the overlap portion may fail.
Thus, a packaging container is formed while the overlap portion is deviated from the predetermined position.
An object of the present invention is to solve the above-mentioned problem in the conventional filling apparatus and to provide a filling apparatus capable of reliably correcting the position of an overlap portion.